MySQL - Detailed code solution to the MySql 8-hour problem caused by using c3p0 and DBCP connection pool

This article describes in detail the detailed code solution to the MySQL 8-hour problem caused by using c3p0 and DBCP connection pool. It has certain reference value. The following is a detailed description.

1. Problem description

I am currently working on a Java Web project, the framework is Spring MVC+JPA, using c3p0 connection pool, the release environment is Tomcat 7, the project has been running for a period of time ( About a few hours), when accessing later, an error message will appear for the first access, but normal access will occur again, and this problem will occur multiple times. The following is the error log:

org.springframework.transaction.CannotCreateTransactionException: Could not open JPA EntityManager for transaction; 
nested exception is javax.persistence.PersistenceException: org.hibernate.TransactionException: JDBC begin transaction failed:   
        at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:428)  
        at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:372)  
        at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:417)  
        at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:255)  
        at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:94)  
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)  
        at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:631)  
        at com.appcarcare.cube.service.UserService
    EnhancerByCGLIB
    a4429cba.getUserDao(<generated>)  
      
        at com.appcarcare.cube.servlet.DataCenterServlet$SqlTimer.connectSql(DataCenterServlet.java:76)  
        at com.appcarcare.cube.servlet.DataCenterServlet$SqlTimer.run(DataCenterServlet.java:70)  
        at java.util.TimerThread.mainLoop(Timer.java:555)  
        at java.util.TimerThread.run(Timer.java:505)  
    Caused by: javax.persistence.PersistenceException: org.hibernate.TransactionException: JDBC begin transaction failed:   
        at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1387)  
        at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1310)  
      
        at org.hibernate.ejb.AbstractEntityManagerImpl.throwPersistenceException(AbstractEntityManagerImpl.java:1397)  
        at org.hibernate.ejb.TransactionImpl.begin(TransactionImpl.java:62)  
        at org.springframework.orm.jpa.DefaultJpaDialect.beginTransaction(DefaultJpaDialect.java:71)  
        at org.springframework.orm.jpa.vendor.HibernateJpaDialect.beginTransaction(HibernateJpaDialect.java:60)  
        at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:378)  
        ... 11 more  
    Caused by: org.hibernate.TransactionException: JDBC begin transaction failed:   
        at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.doBegin(JdbcTransaction.java:76)  
        at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.begin(AbstractTransactionImpl.java:160)  
      
        at org.hibernate.internal.SessionImpl.beginTransaction(SessionImpl.java:1426)  
        at org.hibernate.ejb.TransactionImpl.begin(TransactionImpl.java:59)  
        ... 14 more  
    Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure  
      
    The last packet successfully received from the server was 1,836,166 milliseconds ago.  
    The last packet sent successfully to the server was 29,134 milliseconds ago.  
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)  
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)  
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)  
        at java.lang.reflect.Constructor.newInstance(Constructor.java:526)  
        at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)  
        at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1117)  
        at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3567)  
        at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3456)  
      
        at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3997)  
        at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2468)  
        at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2629)  
        at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2713)  
        at com.mysql.jdbc.ConnectionImpl.setAutoCommit(ConnectionImpl.java:5060)  
        at com.mchange.v2.c3p0.impl.NewProxyConnection.setAutoCommit(NewProxyConnection.java:881)  
        at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.doBegin(JdbcTransaction.java:72)  
      
        ... 17 more  
    Caused by: java.net.SocketException: Software caused connection abort: recv failed  
        at java.net.SocketInputStream.socketRead0(Native Method)  
        at java.net.SocketInputStream.read(SocketInputStream.java:150)  
        at java.net.SocketInputStream.read(SocketInputStream.java:121)  
        at com.mysql.jdbc.util.ReadAheadInputStream.fill(ReadAheadInputStream.java:114)  
        at com.mysql.jdbc.util.ReadAheadInputStream.readFromUnderlyingStreamIfNecessary(ReadAheadInputStream.java:161)  
        at com.mysql.jdbc.util.ReadAheadInputStream.read(ReadAheadInputStream.java:189)  
        at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:3014)  
        at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3467)  
        ... 25 more

2. Cause analysis

The default "wait_timeout" of MySQL server It is 28800 seconds or 8 hours, which means that if a connection is idle for more than 8 hours, MySQL will automatically disconnect the connection, but the connection pool thinks that the connection is still valid (because the validity of the connection is not verified). When the application applies to use this connection, it will cause the above error

3. Solution

There are three ways to solve this problem. The second one is recommended:

1. Increase the value of MySQL's wait_timeout attribute

Modify the configuration file my.ini file in the mysql installation directory (if there is no such file, copy the "my-default.ini" file to generate a "copy my- default.ini" file. Rename the "copy my-default.ini" file to "my.ini") and set
## in the file

##

wait_timeout=31536000  
interactive_timeout=31536000

The default of these two parameters The value is 8 hours (60*60*8=28800).

Note: 1. The maximum value of wait_timeout is only allowed to be 2147483 (about 24 days)

2. Modify the configuration file in the way provided by most articles on the Internet, you can also use the mysql command to modify these two attributes

2. Reduce the lifetime of the connection in the connection poolReduce the survival of the connection in the connection pool period, making it less than the wait_timeout value set in the previous item.

Modify the c3p0 configuration file and set it in the Spring configuration file:

<bean id="dataSource"  class="com.mchange.v2.c3p0.ComboPooledDataSource">       
    <property name="maxIdleTime"value="1800"/>    
    <!--other properties -->    
</bean>

3. Regularly use connections in the connection pool

Regularly use connections in the connection pool so that they will not be disconnected by MySQL due to idle timeout.

Modify the configuration file of c3p0 and set it in the Spring configuration file

<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">    
    <property name="preferredTestQuery" value="SELECT 1"/>    
    <property name="idleConnectionTestPeriod" value="18000"/>    
    <property name="testConnectionOnCheckout" value="true"/>    
</bean>

4. Extension

C3P0

C3P0 is An open source JDBC connection pool, which is distributed with Hibernate in the lib directory, including DataSources objects that implement the Connection and Statement pools specified in the jdbc3 and jdbc2 extension specifications. c3p0 configuration file

<default-config>   
　　<!--当连接池中的连接耗尽的时候c3p0一次同时获取的连接数。Default: 3 -->   
　　<property name="acquireIncrement">3</property>   
　　<!--定义在从数据库获取新连接失败后重复尝试的次数。Default: 30 -->   
　　<property name="acquireRetryAttempts">30</property>   
　　<!--两次连接中间隔时间，单位毫秒。Default: 1000 -->   
　　<property name="acquireRetryDelay">1000</property>   
　　<!--连接关闭时默认将所有未提交的操作回滚。Default: false -->   
　　<property name="autoCommitOnClose">false</property>   
　　<!--c3p0将建一张名为Test的空表，并使用其自带的查询语句进行测试。如果定义了这个参数那么   
　　属性preferredTestQuery将被忽略。你不能在这张Test表上进行任何操作，它将只供c3p0测试   
　　使用。Default: null-->   
　　<property name="automaticTestTable">Test</property>   
　　<!--获取连接失败将会引起所有等待连接池来获取连接的线程抛出异常。但是数据源仍有效   
　　保留，并在下次调用getConnection()的时候继续尝试获取连接。如果设为true，那么在尝试   
　　获取连接失败后该数据源将申明已断开并永久关闭。Default: false-->   
　　<property name="breakAfterAcquireFailure">false</property>   
　　<!--当连接池用完时客户端调用getConnection()后等待获取新连接的时间，超时后将抛出   
　　SQLException,如设为0则无限期等待。单位毫秒。Default: 0 -->   
　　<property name="checkoutTimeout">100</property>   
　　<!--通过实现ConnectionTester或QueryConnectionTester的类来测试连接。类名需制定全路径。   
　　Default: com.mchange.v2.c3p0.impl.DefaultConnectionTester-->   
　　<property name="connectionTesterClassName"></property>   
　　<!--指定c3p0 libraries的路径，如果（通常都是这样）在本地即可获得那么无需设置，默认null即可   
　　Default: null-->   
　　<property name="factoryClassLocation">null</property>   
　　<!--Strongly disrecommended. Setting this to true may lead to subtle and bizarre bugs.   
　　（文档原文）作者强烈建议不使用的一个属性-->   
　　<property name="forceIgnoreUnresolvedTransactions">false</property>   
　　<!--每60秒检查所有连接池中的空闲连接。Default: 0 -->   
　　<property name="idleConnectionTestPeriod">60</property>   
　　<!--初始化时获取三个连接，取值应在minPoolSize与maxPoolSize之间。Default: 3 -->   
　　<property name="initialPoolSize">3</property>   
　　<!--最大空闲时间,60秒内未使用则连接被丢弃。若为0则永不丢弃。Default: 0 -->   
　　<property name="maxIdleTime">60</property>   
　　<!--连接池中保留的最大连接数。Default: 15 -->   
　　<property name="maxPoolSize">15</property>   
　　<!--JDBC的标准参数，用以控制数据源内加载的PreparedStatements数量。但由于预缓存的statements   
　　属于单个connection而不是整个连接池。所以设置这个参数需要考虑到多方面的因素。   
　　如果maxStatements与maxStatementsPerConnection均为0，则缓存被关闭。Default: 0-->   
　　<property name="maxStatements">100</property>   
　　<!--maxStatementsPerConnection定义了连接池内单个连接所拥有的最大缓存statements数。Default: 0 -->   
　　<property name="maxStatementsPerConnection"></property>   
　　<!--c3p0是异步操作的，缓慢的JDBC操作通过帮助进程完成。扩展这些操作可以有效的提升性能   
　　通过多线程实现多个操作同时被执行。Default: 3-->   
　　<property name="numHelperThreads">3</property>   
　　<!--当用户调用getConnection()时使root用户成为去获取连接的用户。主要用于连接池连接非c3p0   
　　的数据源时。Default: null-->   
　　<property name="overrideDefaultUser">root</property>   
　　<!--与overrideDefaultUser参数对应使用的一个参数。Default: null-->   
　　<property name="overrideDefaultPassword">password</property>   
　　<!--密码。Default: null-->   
　　<property name="password"></property>   
　　<!--定义所有连接测试都执行的测试语句。在使用连接测试的情况下这个一显著提高测试速度。注意：   
　　测试的表必须在初始数据源的时候就存在。Default: null-->   
　　<property name="preferredTestQuery">select id from test where id=1</property>   
　　<!--用户修改系统配置参数执行前最多等待300秒。Default: 300 -->   
　　<property name="propertyCycle">300</property>   
　　<!--因性能消耗大请只在需要的时候使用它。如果设为true那么在每个connection提交的   
　　时候都将校验其有效性。建议使用idleConnectionTestPeriod或automaticTestTable   
　　等方法来提升连接测试的性能。Default: false -->   
　　<property name="testConnectionOnCheckout">false</property>   
　　<!--如果设为true那么在取得连接的同时将校验连接的有效性。Default: false -->   
　　<property name="testConnectionOnCheckin">true</property>   
　　<!--用户名。Default: null-->   
　　<property name="user">root</property>

Configuration in Hibernate (spring management):

<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">   
　　<property name="driverClass"><value>oracle.jdbc.driver.OracleDriver</value></property>   
　　<property name="jdbcUrl"><value>jdbc:oracle:thin:@localhost:1521:Test</value></property>   
　　<property name="user"><value>Kay</value></property>   
　　<property name="password"><value>root</value></property>   
　　<!--连接池中保留的最小连接数。-->   
　　<property name="minPoolSize" value="10" />   
　　<!--连接池中保留的最大连接数。Default: 15 -->   
　　<property name="maxPoolSize" value="100" />   
　　<!--最大空闲时间,1800秒内未使用则连接被丢弃。若为0则永不丢弃。Default: 0 -->   
　　<property name="maxIdleTime" value="1800" />   
　　<!--当连接池中的连接耗尽的时候c3p0一次同时获取的连接数。Default: 3 -->   
　　<property name="acquireIncrement" value="3" />   
　　<property name="maxStatements" value="1000" />   
　　<property name="initialPoolSize" value="10" />   
　　<!--每60秒检查所有连接池中的空闲连接。Default: 0 -->   
　　<property name="idleConnectionTestPeriod" value="60" />   
　　<!--定义在从数据库获取新连接失败后重复尝试的次数。Default: 30 -->   
　　<property name="acquireRetryAttempts" value="30" />   
　　<property name="breakAfterAcquireFailure" value="true" />   
　　<property name="testConnectionOnCheckout" value="false" />   
　　</bean>   
　　###########################   
　　### C3P0 Connection Pool###   
　　###########################   
　　#hibernate.c3p0.max_size 2   
　　#hibernate.c3p0.min_size 2   
　　#hibernate.c3p0.timeout 5000   
　　#hibernate.c3p0.max_statements 100   
　　#hibernate.c3p0.idle_test_period 3000   
　　#hibernate.c3p0.acquire_increment 2   
　　#hibernate.c3p0.validate false   
　　在hibernate.cfg.xml文件里面加入如下的配置：   
　　<!-- 最大连接数 -->   
　　<property name="hibernate.c3p0.max_size">20</property>   
　　<!-- 最小连接数 -->   
　　<property name="hibernate.c3p0.min_size">5</property>   
　　<!-- 获得连接的超时时间,如果超过这个时间,会抛出异常，单位毫秒 -->   
　　<property name="hibernate.c3p0.timeout">120</property>   
　　<!-- 最大的PreparedStatement的数量 -->   
　　<property name="hibernate.c3p0.max_statements">100</property>   
　　<!-- 每隔120秒检查连接池里的空闲连接 ，单位是秒-->   
　　<property name="hibernate.c3p0.idle_test_period">120</property>   
　　<!-- 当连接池里面的连接用完的时候，C3P0一下获取的新的连接数 -->   
　　<property name="hibernate.c3p0.acquire_increment">2</property>   
　　<!-- 每次都验证连接是否可用 -->   
　　<property name="hibernate.c3p0.validate">true</property>

Solution to MySql 8-hour disconnection when using DBCP connection pool

Modify l configuration file:

Modify as follows:

<data-sources>  
      <data-source key="org.apache.struts.action.DATA_SOURCE"                             
      type="org.apache.commons.dbcp.BasicDataSource">  
      <set-property property="driverClassName" value="com.mysql.jdbc.Driver" />  
      <set-property property="description" value="wjjg" />  
      <set-property property="url" value="jdbc:mysql://localhost/wjjg?useUnicode=true&characterEncoding=GB2312" />  
      <set-property property="password" value="12345678" />  
      <set-property property="username" value="wjjg" />  
      <set-property property="maxActive" value="10" />  
      <set-property property="maxIdle" value="60000" />  
      <set-property property="maxWait" value="60000" />  
      <set-property property="defaultAutoCommit" value="true" />  
      <set-property property="defaultReadOnly" value="false" />    
      <set-property property="testOnBorrow" value="true"/>  
      <set-property property="validationQuery" value="select 1"/>  
</data-source>

Among them, testOnBorrow and validationQuery are very important.

testOnBorrow means to check the validity of the connection when obtaining it from the database connection pool.

validationQuery is a SQL statement used for checking. "select 1" executes quickly and is a good detection statement.

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